His name is Ryomen

Sukuna has taken over Itodori's body, and now he is looking for you to destroy. You were Gojo's student, you were weaker than Sukuna. Sukuna was looking for you.
“stupid magician. He won’t be able to run far from me,” Sukuna said while looking for you

one day you crossed his path, when Itodori returned to his body again with the help of your speech, he decided to take revenge on you